Recent world events involving terrorist activities have increased the need to develop an environmentally friendly universal decontaminating solution that possesses non-corrosive and non-toxic properties for the rapid neutralization of lethal chemical and biological warfare (CBW) agents. This need is particularly apparent in military operations in which large area decontamination would be required for aircraft, tanks, carrier ships, facilities, equipment, and terrain, as well as related civilian or homeland defense operations that would involve decontamination efforts by first-responder personnel.
Decontamination solutions presently available for the destruction of CBW agents include Super Tropical Bleach (STB), a highly corrosive hypochlorite-based alkaline solution, and DS2, which possesses highly toxic ingredients of diethylenetriamine and ethylene glycol monomethyl (EGM) ether. These decontaminants have the drawbacks in that they present hazards to the handler(s) and surface materials, as well as adversely impacting the environment, and generate significant waste that requires unique disposal.
Efforts to develop more user-friendly decontaminants have focused on using strong oxidant applications such as ozone, titanium dioxide catalyzed photolysis, organic and inorganic peracids, activated hydrogen peroxide, and peroxygen compounds. For example, U.S. Pat. No. 4,850,729 discloses a decontaminating formulation utilizing “per-salts” such as percarbonate, perborate, persilicate or perphosphate, in dry or aqueous forms, for the purpose of rendering active hydrogen peroxide species. Iron bearing clays were also incorporated to serve as activators for hydrogen peroxide to create reactive radical species, as well as providing thickening properties to the formulation. Similarly, U.S. Pat. No. 6,245,957 describes a formulation in which potassium bicarbonate is mixed with urea hydrogen peroxide to create a peracid of percarbonate to effectively degrade chemical warfare agents. Although both inventions make use of peracid oxidants, neither reveals effectiveness toward biological agents.
The uses of either hydrogen peroxide, or a peroxygen compound such as monopersulfate, have been described as the reactive oxidative species within other multi-component formulations that target decontamination of both chemical and biological agents. U.S. Pat. No. 6,369,288 discloses a surfactant system that contains a peroxygen compound in conjunction with a detergent bleach activator for the purpose of generating peroxycarboylic acid as an active ingredient. Another surfactant based formulation disclosed in U.S. Pat. No. 6,566,574 is the combination of a water-soluble polymer, a corrosion inhibitor, a fatty alcohol, and a catalyst together with the reactive oxidative component, but functions under slightly alkaline pH conditions.
Similar to the chemistry found in U.S. Pat. No. 4,850,729, U.S. Pat. No. 6,569,353 utilizes a ferrous iron bearing salt as an activator for hydrogen peroxide to generate powerful hydroxyl radicals in conjunction with the use of a monopersulfate compound. However, this particular formulation is prepared under acidic conditions in the presence of phosphate and is based in fumed silica media.
As reported by Yang et al. Chem. Rev. 92, 1729 (1992), monopersulfate alone has been shown to be reactive towards the chemical agents of mustard gas (HD) and VX, but only under aggressive acidic conditions. A significant amount of a dissolving agent was also needed in this case to solubilize mustard in solution. U.S. Pat. No. 5,186,946 described the use of monopersulfate for biological disinfection for viruses, bacteria, and spores, by combining with sulfamic and malic acids and polyethylene glycol, but also under acidic conditions.
Overall, the particular formulations described above fail to disclose the inclusion of a ketone-containing compound in the presence of monopersulfate to generate dioxirane oxidative species.
Montgomery J. Am. Chem. Soc. 96, 7820 (1974) is credited with the first observation of in situ generation of dioxirane species, in which ketones were shown to catalyze the decomposition of monopersulfate in solution, as well as enhance oxidative reactivity towards select chemical substrates. Murray Chem. Rev. 89, 1187 (1989) and Adam et al. Acc. Chem. Res. 22, 205 (1989) since provided an extensive cross-reference list on the synthetic transformations of numerous substrates from both preparations of in situ generated dioxiranes and dioxiranes isolated in neat ketone solvents, thereby demonstrating unique and powerful oxidative selectivity and reactivity.
Related dioxirane patents include U.S. Pat. Nos. 5,437,686 and 4,001,131, from the textile industry. Each discloses different formulations comprising a peroxygen compound and a diketone for the generation of dioxirane. The diketones for these particular applications were required as opposed to monoketones in that they demonstrated superior inhibition of dye transfer between fabrics during the cleaning process.
More relevant is U.S. Pat. No. 5,403,549 which discloses a method and composition for disinfecting matter or materials contaminated with bacteria, consisting of a mixture of monopersulfate and a carbonyl-containing compound, identified as either a ketone or aldehyde, for producing dioxirane. Carbonyl-containing compounds tested in the patent included acetone, 2-pentanone, 4-hydroxy-4-methyl-2-pentanone, and camphorsulfonic acid. The '549 patent is limited in its disclosure and application, specifically stating that the use of phosphate buffer within a neutral pH range actually inhibits the biocidal activity of a dioxirane solution towards substrates, and discloses formulations only in room temperature conditions (20°-25° C.) to effectively sterilize equipment. Rather, the '549 formulation requires a buffer utilized within an acidic range of about pH 4 to achieve effective disinfection. Application towards toxic chemical substrates was also not described.
To date, dioxirane-producing formulations have not been utilized in an effective manner under non-corrosive, neutral conditions in the presence of carbonate-type buffers to facilitate degradation of viscous CBW agents. The novelty of the disclosure herein is that powerful oxidative species of dioxirane can be generated rapidly in a cost-effective manner with the main by-products of reaction consisting of environmentally benign carbonate and sulfate salts, thereby aiming to provide an effective CBW agent decontaminating formulation that eliminates, or greatly minimizes the impacts of toxicity and corrosiveness to materials.